Radio receiving system



A ril 13 1928. 1,580,359

c. ,T. ALLCUTT RADIO RECEIVING SYSTEM Filed Dec. 50, 1920 WlTNESSES:INVENTOR ATTORNEY hie . a receiving system bodying the use Patented Apr.is, 1926.

UNITED STATES v PATENT OFFICE...

CHESTER T. ALLGUTT, F PITTSBURGH,

VANIA.

' RADIO RECEIVING SYSTEM.

Application filed December at, 1920. semi N9. 434,021.

Toall whom it may concern;

Be it known that I, CH STER T. ALLoU'r'r,

a citizen of the United States, anda resident V of Pittsburgh, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in Radio'Receiving Systems, of which the folloiwng isa specification. V

My invention relates to radio receiving systems and more especially tosystems employing the beat principle of operation. [The object ofmy'invention is toprovide of unusual sensitivityremof the well knownheterodyne orv beat principle of operation.

Heretofore, in systems employing the beat principle of operation, thebeat currents have been formed by combining locally-generatedhigh-frequency currents and the received impulses. This combination ofthe two currents has resulted in a receiving system that is of unusualsensitivity and, for certain wave lengths, highly selective. Accordingto my invention, I provide a receiving system of unusual sensitivitythat embodies new means whereby the energy of a received impulse maycause the formation of heat currentsin. a local receiving circuit.

More specifically, pulses to varythe relation between two local sourcesof high-frequency currents to cause the passage of variable currents ina localre twolocal sources.

ceiving circuit electrically connected'to the Assuming that the periodsof the two local high-frequency sources are same, the efiect of areceived impulse is to.

cause beat currents to ceiving circuit. I

Assuming a condition in which the frequencies of the high-frequencycircuits are traverse the local resuch that beat currents initiallytraverse the local receiving circuit, the effect of a received impulsemay be suchas to cause-the beat currents to'change in frequency or-todisappear, periodically. x

My invention may best be understood by reference to the accompanyingdrawings, in which: i V "1"" Figure 1 is a diagrammatic view "ofcircuitsand apparatus embodying my invention. Y I jv Fig. 2 shows an alternative"arrangement to that of Fig. 1 for varying between the pair ofhigh-frequencycircuits.

Y Referring.

= respectively.

I causethe received im initially the the relation varying the relationbetween the pair of high-frequency circuits.

' Like numerals are. ap having asimilar function. I g

to Fig. 1, a pair of high-frequency circuits 1 and 2 are electricallyconplied itof'like parts PENN LVANIA, ASSIGNOR rro wEs'rINe- HOUSEELECTRIC & MANUFACTURINGCQMPANY,.A CORPORATION or rE NsYL- nected ,to alocal receiving circuit 3, which comprises a receiving device 4 and arectifier 5, through coupling coils 6, 7,,and ,8, 9, The high-frequencycircuit 1, which comprises a, variable capacitance 11,

transformer 14. The high-frequencycircuit- 2 is 'similar'to thehigh-frequency circuit 1 in that it also contains an are 25, a variablecapacitance 11 and an inductance coil.

The antenna circuit 13 comprises an antenna 15 which is connected to aground'lead 16 through an inductance coil 17. The inductance. coil 17.is' shunted by a circuit which includes a rectifying device 18andasecond the coil 6 and a magnetizing winding 12, is; coupled to anantenna circuit ,13through a of a circuit which inrestricted portion 24whereby small changes in the currents traversing themagnetizing winding19 causes relatively large-changes in the reluctance of the magneticcircuit through the magnetizing windings 12, 1'9 and 23 by reason of thesaturation of said restricted portion'24c.

The high-frequency circuits 1 and "2 may be energized 'by any means wellknown to theart. I In the drawings, the high-fre quency currents aregenerated in circuits 1- and 2 by means of an are 25 that is fed from asource of direct-,cur'rentenergy 26 through reactance coils. 27 .1 Theperiods of the highfrequency circuits 1 and. 2 may be varied byadjusting either the variable capacitance 11 "orthe inductance of coils'6 and 8 respectively. Y

Referring to Fig. 2, the arrangement shown differs from that of Fig.1in-the means for varying the relation between-the highafrequencycircuits 1 and 2. In this arrangement, a' resistor .28 having such.temperature coeflicient that incoming signal im Cal pulses materiallyaffect the resistance of said resistor is included in the antennacircuit 13, and also is conncced in shunt relation to the inductancecoil6 through a conductor 29 and a circuit including a variablecapacitance 31. The high-frequency circuits 2 are energ zed in a mannersimilar to that shown in Fig. 1. V

The arrangen'ient shown in 3 ditl'ers from that of Fig. 2 in theutilization of a vacuum-tube device 33 for shunting an inductance coil34 Whichis included in a highirequency oscillating circuit'35. The vacuum-tube device comprises anevacuated bulb 36 having a pair of hotelectrodes 37 and 3S and a plate 39 located therein. The hot electrodes37 and 33 are energized by any means (not shown) WQll known to the art.The plate may be given a negative bias by-mcans of a battery 40. Theanode 39 and the hot cathode 37 are connected to opposite terminals 01"the inductance coil l'l'and through conductors 4 1 and 42, respectively.

The hot cathodes 37 and 33am connected to opposite terminals of the coil34: through aconductor 43 and a conductor 44:, Which includes a variablecondenser 45, respectively.

The high-frequency oscillating circuit differs from circuit 2 in theutilization of the pair of inductance coils 3 and 6 in place of theinductance coil 8.

The antenna 15 is connected to the ground conductor 16 through aparallel resonant circuit which comprises the inductance coil 17 and avariable capacitance a6. The local receiving circuit 3 is similarto thatof Figs. land 2.

Upon a supply of energy to the ares 25, high-frequency currents traversethe cira cuits 1 and 2. The periods of the currents,

as hereinbetore stated, may be adjusted by varying either the variablecapacitance 11 or the inductance of coils 6 and SWlllCl] are included inthe high-frequency circuits 1 and respectively. Assuming the periods ofthe high-frequency circuits 1 and 2 to be. substantially equal, or theperiod of the beat currents to be belou that of an audible frequency,and assuming that the connections of the coils 7 and 9 are such that thecurrentsin the'local receiving circuit are additive, a high-frequencycurrent traverses the local receivlng current 3 upon supplying energy tothe arcs 25. By reason of the high-frequency of the currents traversingthe local receiving circuit 3, or the lOW frequency of the beat-note,substantially no effect is. observed inztheureceiving device 4.

Upon the receipt of Wireless signals, the

effect of the voltage drop across o the induc- 'ta nce coi 17 is tocause currents toztraverse the circuit includin imagnetizlng Winding 19and the rectifier .18. The rectifier 18 2 may be so changed twohigh-frequencycircuits 1 and 2 causes the formation of'beat currents inthe local receivingcircuits 3. The period oi the beat currents 1Sdependent upon the change in the inductance oi the coil 12 that isproduced. by the received impulses. The beat currents may be etccted byany means Well known to the art, such for example, as a rectifier 5 anda receiving device l.

Referrin to Fig. 2, the arrangement shown di' from that of Fi 3 in theprovision of a resistance eh for eil'ecting changes in the relation ofthehigh-frequency circuits 2.

the receipt 1 have found that the high-frequency circuits as te -resultin the production of heat currents of substantially an audible frequencyin the localreceiving circuit Referring to-Fig. 3, upon the energizationof the high-frequency circuit 35, the electrons emitted by the cathodes37 and 38 are attracted to the one or the other of the cathodes,depending-upon which cathode is the more-positive of the two. As theimpedance of the circuit which includes the cathodes 3. and 3S,condenser coil 54.- and conductors 43 and 44 is very high, onlyrelatively small currents traverse said circuit.

I have found, however,that-the impedance of the vacuum-tube device 33,and, therefore, the relation between the circuits 35 and 2, may becontrolled by subjecting the electron stream to a varying electrostaticfield, the value of which is proportional to the intensity of thereceived impulses.

In operation, the period of the parallel resonant circuit, whichincludes the variable capacitance 46 and the inductance 17, is adjustedto that of the incoming signal to cause maximum changes in the intensityof the electrostatic field. The variations in the electrostatic fieldthat are caused by an in coming signal cause corresponding changes inthe relation between the circuits 2 and 35 to cause the formation ofbeat currents in the receiving circuit 3.

In the foregoing description, the effect of an incoming signal has beento vary the relation between the two high-frequency circuits tocause'the formation of beat currents in the local receiving circuit 3.It isobrelation between the Upon a small change in'the re- 5. SlBtL ceelement 28, by reason of of a Wireless wave,

vions, to: one skilled in the art','that the reverse procedure isequallyapplicableto my That is, the beat currents may initially traverse thelocal rethe efi'ect of a received impulse being merely to cause the beatcurrents to periodically disappear or change in pitch.

The advantage ofmy provision of a simple, sensitive receiving system.While I have shown of my invention,

arrangement is the eiiicient'and highly three embodiments 1t lscapableof various other modifications in the meansfor varying the relationbetween the pair of high-frequency circuits without departing from thespirit ofmy. invention.

I desire," therefore,

that only such i limitations shall be imposed thereon as are indicatedin the appended claims, I claim as my mventionz 1. In a radiotelegraphic rec eiving device, two circuits tuned to approximately thesame frequency, means for maintaining oscillations in each of saidcircuits, means re sponsive to the difference of frequency between saidcircuits for producing signals and means responsive nalling energy tothe received sigf'or altering the frequency of one of said circuits,said last named means comprising a magnetic core and a device includinga rectifier for altering the average amount of flux in said core duringthe reception of signalling energy.

2. In a radio telegraphic receiving device,

two circuits tuned to approximately the same frequency,

means for maintaining oscillations in each of said clrcuits, meansresponsive to the difference of frequency between said circuits'forproducing signals and means responsive to energy for altering thereceived signalling. the frequency of one of said circuits, said lastnamed means comprismg a rectifier and of said tuned circuits.

vice, two circuits tuned to ap a winding in series, and a core common tosa1d winding and to a part responsive to the diiference'of frequencybefrequency, means for maintaining tween said clrcuits for producingsignals and means responsive to the received signalling energy foraltering the frequency of one of said circuits, said last named meanscomprising a magnetic core, adjust-able flux producing means formaintaining said core at a sensitivemagnetization, a winding on saidcore included in said tuned circuits, a second winding on said core andmeans including a rectifier for delivering-signalling energy to saidsecond windin 4:. In a radio telegraphic receiving device, two circuitstuned to approximately the same frequency, means for. maintainingoscillations in each of said circuits, means responsiveto the differenceof frequency be tween said circuits for producing signals and meansresponsive to the received signal ling energy for altering the frequencyof one of said circuits, said last named means comprising 7 branchedmagnetic circuit, adjustable flux producing means for maintaining saidcore at a sensitive magnetization, a winding on said core included insaid tuned circuits,a second winding on said core and means ingludin'g arectifier for delivering signalling energy to said second winding. 7

In a radio telegraphic receiving device, two circuits tuned toapproximately the same frequency, means for maintaining oscillations ineach of said circuits, means responsive to the diflerence of frequencybetween said circuits for producing signals and means responsive to thereceived signalling energy for altering the inductance in one of a coilfed through said rectifier and a magof said circuit.

In testimony subscribed my name ber, 1920.

whereof, I have hereunto this 21st day of Decem- CHESTER T. ALLCUT-T.

netic circuit'common to said coil and a part a magnetic core iorm'mg anunsaid circuits including-a rectifier, 1'

